IDS Forum

Re: Running out of virtual mem segments

Posted By: Keith Simmons
Date: Friday, 2 May 2008, at 3:52 a.m.

In Response To: Running out of virtual mem segments (MARGARITA CRUZ)

On 30/04/2008, MARGARITA CRUZ <margarita.cruz@dhl.com> wrote:
> This problem has been a constant issue on our production server for years,
> according to my previous manager, Informix support has been called to solve
> this issue years ago, but was unable to provide a resolution. What we have
> been doing to prevent this is to re-start the unix process that calls the 4gl
> code several time a week. Here is a general description of the problem:
>
> Environment : HPUX 11, IDS 7.31.Uc6AXF, 4gl 7.30.HC4
> Program structure:
> 1) Parent unix shell - this shell runs (constantly) on the background, sleeps
> for 30 seconds, then checks if there are files to be processed in directory a.
> If there are no files, sleeps again for 30 seconds, and awakes to check. If
> there are files, calls child unix shell script using "exec child.sh" and then
> exits
> 2) Child shell - this script processes the files by calling a 4gl program and
> after files are processed, calls the parent shell to check for files again,
> using "exec parent.sh"
> 3) 4GL program - uses dbload to load the files into table A then re formats
> the data for insertion to table B
>
> Problem:
> After several days of the scripts and 4gl running, there comes a point when
> the system will run out of virtual mem segments. At this point, we find that
> the 4gl program is hanging, in the middle of processing a file, with no
> apparent error or reason to hang (if we re-process the file it loads ok). And
> also, that the 4gl program has requested hundreds of segments until online
> runs out.
>
> We clear the issue by killing the hanging processes, and then the segments are
> automatically freed.
>
> We would like to know if others have had a similar setup, and may provde
> suggestions before we change the process logic, we are thinking of using a
> cron instead of a unix daemon that is constantly running.
>
> Regards,
> MCruz
>
>
> *******************************************************************************
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>
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>

MARGARITA

Many others have suggested looking at shmem, increasing it, removing
unused segments. Might I suggest looking at the scripts themselves.
Running a parent which execs a child which execs the parent which
execs the child etc.etc. does not seem particularly good. I would
suggest it would be better to leave a single parent running
continuously and check for files every 30 seconds, but then simply
call the child, which calls the 4GL and then returns rather than
exec'ing the parent.
I think the long chain of execs is where you are losing memory.

Keith

Messages In This Thread

• Running out of virtual mem segments
  MARGARITA CRUZ -- Wednesday, 30 April 2008, at 3:36 p.m.
  • Re: Running out of virtual mem segments
    MIKE MAGIE -- Thursday, 1 May 2008, at 10:33 a.m.
  • RE: Running out of virtual mem segments
    Robert Roussey(IT) -- Thursday, 1 May 2008, at 12:11 p.m.
    • Re: RE: Running out of virtual mem segments
      RALPH GENTRY -- Thursday, 1 May 2008, at 12:27 p.m.
      • Re: RE: Running out of virtual mem segments
        H.G -- Friday, 2 May 2008, at 2:53 a.m.
  • RE: Running out of virtual mem segments
    Scott Mackenzie -- Thursday, 1 May 2008, at 7:51 p.m.
  • Re: Running out of virtual mem segments
    Keith Simmons -- Friday, 2 May 2008, at 3:52 a.m.

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